1. Technical Field
The present invention relates generally to a closure assembly for a shipping and storage container, and more particularly toward a closure assembly for reducing leakage through a discharge outlet in a fluid containing vessel.
2. Background Art
Shipping and storage containers which have a cylindrical drum and removable lid are generally well known for reliably storing and/or transporting a variety of materials. In order to fill the drums, the lid is removed to define an opening in one end face of the drum and material is introduced into the drum. After filling is completed, the lid is replaced and appropriately secured to the drum to seal the drum and prevent the contents from spilling or otherwise escaping during storage and/or transportation of the drum.
In applications where a portion of the contents is to be emptied from the sealed drum, the drum is provided with a discharge outlet. A suitable closure element, such as a threaded plug, is received in the discharge outlet for preventing the undesired escape of the contents of the drum. When it is desired dispense a portion of the contents, the closure element is removed and material flows through the outlet under the effect of gravity. An atmospheric pressure-admitting inlet often is provided to facilitate the dispensing process.
The manner in which a closure element engages the drum opening can contribute to excessive leakage through the opening, even when the closure element is properly installed. As a result, prior closure elements have a rubber annular washer between the closure element and the drum.
In one known material container, a closure element has a cylindrical threaded plug with an oversized axial end. The plug is receivable in an internally threaded upstanding boss in a drum and has a rectangular radially outward opening groove adjacent the oversized end. A generally flat annular washer is provided and has a radially inward directed lip which is seated in the rectangular groove in the plug. When the plug is tightened into engagement with the container, the washer is held between the oversized end of the closure element and the boss.
Due to limited engagement of the lip on the washer with the plug, the washer is susceptible to falling off the boss and breaking the seal between the closure element and the drum. In addition, if the washer is not completely flat or does not have a uniform thickness, the washer will not seal around the total periphery of the boss and can permit unacceptable levels of leakage through the discharge outlet. The present invention is directed toward overcoming the problem set forth above.